Header Stuff

[robby1870]

Alright, got some questions. When I build this motor, Im make some headers, and Ive already started some of the design. Ive been using the heads from the motor to design the flange, which already designed in Mechanical Desktop (if anyone knows what that is). I measured the stock exhaust port size on my Gen II heads and got right at 30mm (1.18in), diamter. I was thinking of porting it to 32mm (1.26in) and having something close to a 1.5in diameter primaries, and having the primaries about 5 feet long (based somewhat off the equation in the header section). I'll be using the Crane 272-2, bored .040 over and around 11.4:1 compression, ported heads, etc. What do those of you that know about this stuff or have made your own think? I havent gotten to collector design yet.

[bszopi]

There is no way in the world you will ever get 5' long primaries!! GM recommended a primary length of around 32" IIRC, which would still be kind of a pain to fit, but is do-able.

[robby1870]

I was going to try for true duals, so no crossover. I thought 5' seemed awful long, so I'll shoot for 3' primaries

[robby1870]

Anyone else have any input?

[RacerX11]

When I built mine, I used 1-5/8" primaries. Don't forget that exhaust tubing is measured by the outside diameter, so 1-1/2" pipe is only 1.40" ID (for 0.049 wall tubing). The 1-5/8" is 1.535" ID.

On the prmary length, I think fitting 36" primaries is going to be a tight fit. I used the dimensions in the GM Power manual whenI built mine (1-5/8" x 32" primaries, 2-1/2" collector). Even the 32" primaries are tough to cram into the engine compartment on a FWD car.

Marty

[StudlyCamaro]

what tubing are you plannig on using for the headers? mandrel bends? and good luck on 3 foot primaries.. thats a lot of crap to cram under a hood

[robby1870]

what tubing are you plannig on using for the headers? mandrel bends? and good luck on 3 foot primaries.. thats a lot of crap to cram under a hood

Yeah, mandrel bends. I'll prolly have to go with the 32" primaries that have been mentioned. Its still in the early stages, but I just wanna get it all planned out and ready to go